This collaborative proposal has Imaging, Biomechanics and Vascular Biology components. This combined submission seeks to identify imaging, hemodynamic, elastomechanical and pathobiologic parameters that distinguish the vulnerable atherosclerotic plaque. The Imaging component will develop and validate MR angiographic methods that yield high resolution 3D measurements of the carotid bifurcation in patients about to undergo endarterectomy. Plaque lumenal contour and composition will be validated by ex vivo MR imaging and histologic studies. Currently, identification of the specific features that make any given plaque vulnerable to rupture is hampered by the absence of a reliable, non-invasive method that can serially monitor plaque morphology in asymptomatic subjects. The coupling of high-resolution imaging with the pathophysiologic findings provided by the Biomechanics and Vascular Biology groups will allow identification of the plaque characteristics which define the vulnerable plaque. Armed with this data we could embark on a prospective monitoring program to define patients at risk.